Pump control mechanism



July 13, 1948.

Filed A ril 11, 1945 W. W. PAGET PUMP CONTROL MECHANISM 6 Sheets-Sheet 1 Am mm.

' Filed April 11, 1945 July 13, 1948. w w, j' 2,444,952

PUMP CONTROL MECHANISM 6 Sheets-Sheet 2 w; A-Wvwm' July 13, 1948. w. w. PAGET PUMP CONTROL MECHANISM 6 Sheets-Sheet 3 Filed April 11, 1945' lflvmiow W622 ffagd J? m ens/1v "mun:

TO A 17105 PHERE' 02 2 4 2 7 a a/m4 y 3. 1948- w. w. ma-

PUMP CONTROL IECHANI SI 6 Sheets-Sheet 4 I Filed A ril 11, 1945 July 13,1948. W.WI.PAGETI 2,444,952

PUMP CONTROL MECHANISM 6 Sheeis-Sheet 5 Filed April 11, 1945 122%22307: ZJZ'ZZ Mfd tl Jul 13, 1948.

Filed April 11, 1945 W. W. PAGET PUMP CONTROL MECHANISM 6 Sheets-Sheet 6 A "Mann Patented July 13, 1948 WinW. Paget, Michigan City,

Joy Manuiacturing Company,

Pennsylvania Application April 11,1945, sim

' '23 Claims. (ores-1.5)

My inventionrelates to air pumping apparatus, ing automatically the pumping apparatus;

In the pressurizing of an aircraft cabin itvis and more particularly to means for regulatdischarge of fluid by a.

customary to deliver air from a supercharger or ,compressor to the cabin, and to vent'the air from the cabin at a rate to maintain the desired pressures therein. 1 With a cabin pressure vent or control valve of ordinary construction there will be a maintenance of thedesired cabin pressure not withstanding a relatively widely varied supply rate of air to the cabin, Accordingly, there improved control meansresponsive to .such

Ind.,-assignor to a corporation of produced 'byyariations in mass flow of air in a compressor discharge line, and operative in response to such pressures for maintaining the mass flow in the discharge line substantially constant. Another object is to provide, for a compressor discharging air to-an aircraft cabin, ambient pressnresand to pressure diflerentials produced. by variations in mass flow of air in the compressor discharge line, and operative in responseto pressures for maintaining the flow oi air through the discharge line substantially constant during flight, below a predetermined eleis an opportunity tor a substantial waste or power in the compressor and the pumping of air in an unnecessary excess to the cabin.

According to my invention it bleed air from the cabin pressurizer in such a manner that the amount delivered will be held relatively constant at substantially the desired rate during flight'below a predetermined elevation. It is planned to do this by utilizing a device which will regulate the venting under the control of pressure differentials created by variations in mass flow or air to the cabin, high mass flow creating high differentials that increase bleeding and reduce flow to the cabin, and diminished mass flow resulting in reduced pressure difierentials which cause diminished bleeding. It is further planned to superimpose on this control a control which is responsive to ambient pressure and which shall, as ambient pressure drops below cabin pressure, cause greater and greater degrees of reduction in bleeding to attend like pressure differentials, and which, at the ambient pressure existing at the predetermined elevation, eflects a closure of the bleeding device so that the compressor discharges all of its air at full compression to the cabin, and the differential pressure produced by variation in mass flow then becomes entirely ineffective in the control of the bleeding device.

' An object of my invention is to provide improved means for controlling the delivery or air toan aircraft/ cabin. Another object is to is proposed to vation and pression through for delivering to the cabin alter comthe full built-in compression ratio all of the air taken into the compressor provide improved means for controlling the discharge of air from a compressor to an aircraft cabin so as to maintain the supply of air to the latter relativelyconstant during flight below a predetermined elevation. Still another object is to provide improved means, responsive to the mass fiow of air in a discharge line of a compressor for regulating the bleeding of air from the compressor. Yet another object "is to provide improved means responsive to pressure difierentials during flight above the predetermined elevation. Other objects of my invention will appear in the course of the following description.

In the accompanyingdrawings there are shown for purposes of illustration two forms which the invention may assume in practice.

In these drawings:

Fig. 1 is a horizontal longitudinal sectional view of a pumping apparatus, with parts shown in elevation, the view being taken on the plane of the line l-l of Fig. 4.

Fig. 2 is an enlarged, fragmentary sectional view taken onv the plane at Fig. 1.

1 Fig 3 is a further enlarged, sectional view taken on the plane of, Fig. 2, showing only a portion of the control means for the hydraulic system.

Fig. 4 is a vertical sectional view taken on the plane of the line 4-4 of Fig. l.

Fig. 5 is an enlarged iragmentary transverse section on the. plane of the line 5-5 of Fig. 4.

Fig.6 is a section on the planes of the line 6-6 of Fig. 5. Fig. 7 is a plan view, with parts shown in section, of the pumping apparatus of Fig. 1.

Fig. 8 is a vertical sectional view on the plane oi the line 8-8 of Fig. 4, showing the intake end of the pumping apparatus of Fig. 1.

Fig. 9 is a vertical sectional view taken on the plane of the line 5-9 of Fig. 1, showing the high Fig. 11 is a schematic diagram showing the location of the unloading port with respect to the rotors when viewed from the side or the pumping apparatus at which the unloading port is located.

3 Fig. 12 is a sectional view, with parts shown in elevation, of a different form of pumping apparatus having my improved control means associated therewith.

The pumping apparatus shown in Figs. 1 to 11,

- except for the discharge connections and certain control means, is similar to that shown in my copending application, Serial No. 452,299, filed in the form shown in Fig. 10, with six helically arranged grooves ll each adapted to cooperate with the lobes of the rotor 4, and the leading concave surfaces l2 of the grooves II are in' profile substantially in the form of an arc to coact with the arcuate pressure surfaces ill of the lobes of the rotor 4, while the following concave surfaces I4 of the grooves Ii are generated curves in profile. A different form of rotor construction, or even quite a different type of compressor, may be used if desired without departing from various aspects of my invention, With the rotors constructed and arranged as illustrated, it will be evident that they will have low and high pressure ends.

The rotors are adapted to operate with space packing; that is to say, they are maintained in such relation to each other, through gearing, that there is no actual contact between the rotors, but such close spacing that at thehigh speeds of operation there is negligible leakage. The rotors 4 and 5 are supported at their low pressure ends, as shown in Fig. 4, by stub shafts i6 and il which are, in turn, supported in bearing sleeves l8 and i3 received within bores 20 and 2| in an end casing portion 22 formed integral with the casing 3. The high pressure ends of the rotors are also provided with stub shafts, l6 and ll (Fig. 9), which are also supported in suitable bearings. The casing 3 is provided with an intake chamber 2% with which an intake passage 25 communicates, and the intake chamber communicates with the right-hand, low pressure ends of the rotors, and also for a substantial part of the length. of the rotors communicates with the back portions thereof, the portions of the rotors at the sides of the latter opposite the discharge. The casing 3 is also provided with a discharge chamber 26 at the high pressure ends of the rotors (the left-hand ends thereby as viewed in Fig. 1), and with another chamber 21', whose purpose will later be described.

For the purpose of maintaining the rotors out of contact with each other they are connected at their discharge ends by intermeshing helical gears 30 and 3|, the gear 30 being splined to the stub shaft l6 supporting the rotor 4, and the gear 3| being splined to the stub shaft I'l' supporting the rotor 5. Regardless of the speed at which the rotors turn, these gears operate to maintain the space packing heretofore referred to; in other words, a very small clearance. between the surfaces of the lobes and the sides and bottoms of the grooves of the rotors is maintained, thus preventing wear and permitting the operation of the pump at high speeds. By reason of the smallness of the clearance maintained and the high speeds Of rotation, serious leakag is prevented, as above noted. The gear 3| is connected by a one-way clutch to a drive shaft for effecting rotation of the rotors during starting and during those periods in which the drive shaft is turning at comparatively slow speeds. Arranged at the discharge ends of the rotors are gears 33 and 34 for driving the rotors at comparatively high speeds. The gear 34 is connectible to the drive shaft by a fluid actuated clutch, and, on the application of this clutch by fluid supplied thereto, the gear 34 is connected to the drive shaft and operates to drive the gear 33 which is connected by a shaft 35 to the gear 30. The ratio of the gears 33 and 34 is such that the gear 3|] is driven at a greater speed by these gears more fully disclosed in my application hereinabove identified.

The compressor is provided with a speed responsive device for controlling the supply of an operating fluid, in this case a liquid, to the fluid actuated clutch mentioned above. There is also provided a hydraulically actuated unloading means for the compressor, andmeans responsive to the flow of fluid in the compressor discharge line for controlling the flow of an operating liquid relative to the unloading means so as to maintain relatively constant the supply of fluid from the compressor, to the cabin during flight of the aircraft below a predetermined elevation. Further means responsive to the pressures at the exterior of the cabin are provided for effecting a loading of the compressor when the aircraft goes above the predetermined altitude.

It will be understood that the rotors 4 and 5 cooperate with each other and with the casing 3 to form chambers which diminish progressively in volume as the rotors are caused to rotate. Fluid contained within these chambers is compressed, if no means of escape is provided, until the chambers open into the discharge chamber 26. In order that the supply of air to the cabin may be maintained relatively constant, and that the air supplied may not be unduly compressed so as to cause excessive heating, there is provided an opening 33 through. which air may be vented from the compressor to the chamber 27 which is connected in communication with the space surrounding the aircraft by a conduit 39. The opening 38 communicates with the interior of the casing 3 at such a point between the ends of the rotors that no compression of the fluid takes place before communication with the opening is had; and the. relationship of the opening 38 to the discharge chamber 26 is such thatno compression of fluid will take place between the times when the compression-chambers move out of communication with the opening 38'and when they move into communication with the discharge chamber.

To control the opening 38, there is provided a valve 40 whose shape is such that when the same is closed it conforms very closely to the inner walls of the casing 3. This valve is connected by it the closing movement of the valve to a position injwhich the walls or the valve conform exactly to the surface of the rotor chamber. This valve is adapted normally. to be maintained open by a spring 41 engaging at one end the wall of a member 48 which forms a portion of the enclosure of the chamber 21 and which is secured in any suitable manner to the casing 9. The other 4 end of the spring acts against a piston 50 received within a cylinder bore 5| which is formed in'a cylinder providing member 52 also secured in any suitable manner to the casing 9 in a position overlying the member 40. A piston rod or operating stem 53 is connectedat its outer end to the 'piston 50 and is connectedat its inner end by means of an elongated eye 54 and a pin '09 to the valve 40. The piston 50 and the member 52 cooperate in forming a servo motor 09 to which fluid may be admitted through a passage 51 under the control of means hereinafter described. When the servo motor is not under pressure delivered through the passage 51, the valve 40 is moved to an open position by the spring 41. When, however, sufiicient pressure fluid is supplied to the servo motor, the piston 50 will be caused, through the operating stem 03, to close the valve 40, and the compressor will then operate fully loaded. The pressure fluid used is a liquid, as later shown, so the valve can be maintained in various positions of adjustment. Thus, depending upon the position of the valve 40, there is provided a displacement pump for delivering a reduced quantity of air to the cabin and a compressor which is capable of delivering air under a substantial pressure to the cabin.

As previously indicated, the change in speed in operation of the compressor and the loading and unloading of the compressor are both hydraulically controlled. The liquid for the hydraulic control system is contained within a sump 59 disposed between the lower wall of the rotor housing and an outer wall 00 forming an integral part at opening out of the chamber II. and this pusage communicates with an annular groove 0| in the bushing I0. Communicating with the annular groove 00 are obliquely disposed'passages 90 openinginto a chamber "in thestub shalt II. The chamber 01 is connected by a tube 00 centered within the rotor 4 ior conducting oil to the gears 30, II and 03. 94 for lubricating latter. The oil conducted to these gears is retumed by suitable passage means to the sump 00.

The stub shaft I0 is provided with a valve receiving bore 90 to which 011' may be supplied from the annular groove 09 through obliquely extending passages 9|. Formed in the bushing I9 surrounding the valve receiving bore is an annular groove 99 which is connected with the interior of the bore 90 by radial passages 94. Supi-ported on the outer end of the stub shaft II is a mounting 99 for a speed responsive governor 91 which operates to vary the position of a valve member as in the bore so. Acting between the I valve member 90 and the inner end of the bore 90 is a spring 99 which tends to move the valve member outwardly against the action of the speed responsive device 91. Formed on the valve member adjacent its inner end is a collar I00, and spaced from this collar by an annular groove MI in the valve member is another collar I02, and at the right-hand end of the valve member is an enlarged collar I04 spaced from the collar I02 by an annular groove I05. The collar I04 is slidably supported by the support member 90 for the speed responsive device, and the annular groove I0! is connected by passages I09 in the support member 90 into communication with a chamber V I0! which communicates with the sump 09.

The speed responsive'device 9! includes flyweights I09 which are pivota'lly supported by the of the casing 3. The sump is, in the horizontal position of the compressor, substantially horizontal, and a pump 6| of the intermeshing gear type is positioned at the right-hand end of the sump as viewed in Fig. 4, so that it is partly submerged and so that its intake is always submerged in the oil contained therein. The pump 6| includes a casing 62 containing rotors 83 having intermeshing teeth. Oil is admitted to the interior of the pump casing through a suitable intake passage and is carried around by the teeth of the rotors to a discharge port 64 which communicates with a passage 95 opening into the bore 66 of a sleeve member 01. One of the retors is provided with a shaft 68 which carries a gear 69 meshing witha pinion l0 rotatably supported on the sleeve member 61. A larger gear 12 is formed integral with the gear 10 and is driven by a pinion I3 formed integral with the stub shaft I1. Liquid delivered to the bore 66 of the sleevemember 61 is discharged through a passage I5 into a chamber I6 containing a strainer 11. The liquid passes through the trainer 11 to a passage 18 which opens into an annular groove I9 formed in the inner periphery of the bearing bushing I9. The opposite side of the annular, groove I9 opens into a passage 90 which communicates at its upper end with a chamber M. The chamber 8| constitutes a distribution point for oil for lubricating purposes and for operating the speed changing clutch mechanism,

previously described, and for closing the valve 40. In line with the passage is another passage support member 96. These flyweights carry ad-' Justable screw devices I09 which engage theouter end of the vavle member and, upon attainment of the shaft It to a predetermined speed of rotation, the flyweights actuate the valve member to shift it from a position in which the annular groove IOI connects the passages 9| and 94 in communication with each other to a position cutting of! the communication between these passages and connecting the passages 94 "in communication with the annular. groove I05 thereby allowing fluid entering the bore 90 through the passage 94 to be vented while at the same time preventing any delivery of fluid from the pump to the radial passages 94. The venting oi'fluid from these passages through the bore 90 will effeet, as shortly described, a reduction in the speed of the rotors. This reduction in speed,

however, will not be suillcient to effect an operation. of the speed responsive device which permits the valve to move again to a position for supplying fluid to the passages 94, as the design of the governor is such that it becomes operative to force the valve to the left only upon the attainment of a predetermined speed while, but once assuming this position a falling off of the speed to a much lower speed will be necessary before the weights will be movedin the opposite direction. This subject matter is quite fully described, except for the special relation of the port 99 to the rotors, in my copending applicav tains a rotatable valve .16 having an operating handle III by means of which the valve may be turned into any one of three difl'erent positions. In the position of the valve H6, shown in Fig. 4, a die-metric passage I I8 connects the opening I I3 with an opposite opening H9 in the valve sleeve. and the latter opening communicates with a passage I20 which is connected through a port I2I in the bearing sleeve I9 and an annular groove I22 and radial pa sages I23 with a chamber I24 within the interior of the stub shaft I1.

The chamber I24 is connected by a tube I25 in.

communication with the fluid actuated clutch for controlling the operation of the driving gear 34. It may be pointed out that the valve at speeds of the rotor 4 below a'predetermined'number of R. P. M. will be in the position shown in Fig. 4 and will connect the pump discharge through the ports and passages previously described with the tube I25, but that at speeds above such a predetermined number of R. P. M. the valve 98 will be moved to the left to cut off communication completely between the passages 84 and H2 and to vent passage H2 back to the sump through the chamber I01.

The mode of operation of the mechanism, so far described, is as follows: When the compressor is started, a driving connection is immediately established between the drive shaft and the gear 3|, and the pump 6| commences to deliver fluid through the passage 65 to the strainer 11, where the fluid is strained and then conducted through the passages 18 and 60, the chamber 8|, the passages 84 and I, the annular groove I0 I, the radial passages 94, the passages H2, H8 and I20, and the tubular conduit I25 to the fluid actuated clutch for the gear 34. The clutch will be actuated by the fluid supplied thereto for connecting the gear 34 to the drive shaft so that driving of the compressor will take place through the gears 34, 33, the shaft 35 and the gears 30, 3|. The

sage HI and the bore.

bounding wall of the chamber 0|. when the valve is turned so as tobring the groove I35 into communication with the passage I20, fluid will be supplied from the chamber 8 I continuously to the passage I20 and the tube I25, and high-speed drive of the compressor will alone be possible.

The chamber 81 communicates with a laterally extending passageway I31, as shown in Figs. 1 and 2. This passage is adapted to be connected under the control of a spring loaded valve I38 with a passage I39 opening into a longitudinal slot which opens into an annular chamber I40 surrounding the sleeve H4 and connected at its opposite side with a longitudinal slot which connects with a passage I'4I. The function of the spring loaded valve I38 is to maintain suflicient pressure in the'chamber 6| under all circumstancesuwhen the compressor is running toinsure the operation of the speed change mechanism. The passage I4I communicates with a bore I42, and a valve I43 is reciprocably contained within this bore and is urged by a spring I45 acting against an adjustable follower I41 toward a position cutting all communication between the pas- A vent port I46 opens v out of the bore I42 into the chamber I01 communicating with the sump. A port I50 connects compressor will then be driven at a high speed which will be continued until the speed becomes such that valve 98 is shifted by the speed responsive device 91 to cut off the supply of fluid from the pump to the passage H2 and to connect this passage through the annular groove I05 and the chamber I01 to the sump. The venting of fluid from the fluid actuated clutch will result in a release of the driving connection through the gear 34 and will cause drive to take place at a lower speed through the gear 3i.

The manually rotatable valve H5 previously mentioned can be adjusted to such a position as to restore high-speed drive of the compressor after such high-speed drive has beenautomatically interrupted, or to prevent interruption of high-speed drive upon the attainment of the predetermined speed of operation at which a shift to low-speed drive is normally effected. In another position of this valve, the drive of the compressor at a high-speed may be prevented. In addition to the diametric passage H6 formed in the valve H6, there is a longitudinal passage I30, as shown in Fig. 6, which opens into the space I3I at the right-hand end of the valve, a space which is connected by a passage I32 with the chamber I01 which communicates with the sump. When the valve H6 is turned to bring the passage-l30 into communication with the passage I20 and to blank off the port H3, fluid will be vented from the clutch mechanism through the tubular conduit I25, passage I20 and the peripheral passage I30 to the sump. Thevalve H6 also has an oppositely extending peripheral groove I35 opening through its end which forms a portion of the the reduced portion I60.

the passage MI in communication with a bore I 5I in a valve seat member I52 mounted in a passage I53 which is connected by another passage I54 to. the passage 51 leading to the servo motor 56 to which fluid is supplied to actuate the valve 40.

The bore I5I ,opens at one end into the passage I53 and opens at its other end into an enlarged bore I56 in the valve seat member. A valve element I51 has a portion I58 slidably received within the bore I5I and separated by a reduced portion I60 from an enlarged head portion 'I6I which is engageable with the shoulder at the juncture of the bores I5I and I56 for controlling the flow of fluid therebetween. Extending longitu- I dinally through the valve element is a passage I62 opening at one end into the bore I5I, and a port I63 in the valve element connects the passage I62 with the annular space I64 surrounding The bore I56 of the valve seat member is connected by ports I66 with the chamber I01 which communicates with the sump 59 and which has the pressure therein maintained equal to the pressure at the exterior of the cabin by reason of a connection to the exterior through a suitable conduit, not shown. It will be evident that a seating of the valve element I51 cuts oil the flow of fluid from the annular space I64 to the sump and causes all the fluid delivered to the annular space from the passage I4I to be delivered to the servo motor for maintaining the compressor loaded. If the valve element is held unseated sufiiciently, the

fluid in the servo motor as well as the fluid delivered through the passage I4I will be returned to the sump. In order that the pressures acting in opposite directions on the valve element may be balanced, there is provided a bellows device I10 connected at one end to the enlarged head portion I6I of the valve element and connected at its other end to a head member I1I threaded into the bore I56. Ports I12 connect the passage I62 in communication with the interior of the bellows device I10 so that the same pressures act on opposite ends of the valve element, and the effective cross-sectional area of the bellows device is made equal to the area within the seat provided by the member I52 so that the fluid pressure 2,444,952 1 2' lows device I7 will be t e same; a is devi taken into the compressor to be discharged to the will, therefore, eil'ect no control of the alve 'ele conduits 233, and a venting of fluid from th cylment I57 duringsuch flight inder member will result in an opening of the The ressu e on the inner wall or the bellows valve ement so that part or the air will be by device I86 decreases as the elevation increases, passed from the discharge side ore the chamber making it necessary that the rate of do in the 222 to the int e line 230. Th by-passing of discharg line he inc asingly greater to hold'the air. will cause the quantity as well as the pressure compressor oaded as the elevation increases. of the ir deli ered t rough the conduits 233 i: As the aircraft goes abo e 8,000 feet, the preshe cabin to bereduce sure at the interior of the bellows device I78 de- 10 'Th@ conduit 252 is nnected in communicacreases and the pre urea its exterior remains tion with fluid supply I d venting means under equal to the a bient pressure at 8,000 f t. the control of a control mechanism 255 s milar pressure at t e interior of-the bellows device I86 to that described in the first form of my nven- Iso r ain qual to the pressure at 8,000 feet, tion. is contro mechanis includes asing and the pressure at its exterior continues to vary 1.; eleme 256 and 257 connected together by any with the flow or air n th discharge-line, suitable eans and clamping between th a 25,000 eet, the pressure at the interior of the belannlll member 258 to which m e lows evice I 78 beco es such, with the spring lows device 258 is conn ted is hello settin assumed for he spring I76, t 1; th cooperates with recesses in the casin spring I76 is overcome by this bellows device an to form chambers 260 and 26I WhICh a the v lve element I57 is held closed to efiect nected respectively by conduits 2 2 and continuous loadin of the co pressor. Between he mouth nd throat 01 a venturi 26 0 8,000 and 25, 00 feet the valve element I57is sub in the intake line 230. The bellows d v1 Jected o forces which consist of e force pro has a plat 266 closing its other end, a d a duced he bellows device I78, 0 posed by 6 acts between this plate a d an a spring I76, with the superposed forces exerted b tm m r 26 r M818 8' p 11 the spring I92 opposed by t e bellows evice I86 the bello device. A screw 269 threaded th By making the bellows devic I86 relati ely large, an openi g in the casing into engagein compared with the bellows device I78, n l the abutm t member provides for adjus ing the spring I92 proportionally strong, it is 30 he latter Fixed within res 270 and 27! i pOssib fo the contro of the valve I57 between the casing ele cut 256 is a valve seat providing altitudes 01- 8,000 and 25,000 feet be primarily member 272 h ving stepped bores 213 a y the bel ows device last mentioned: It will be om ni i a h other a d c seen t at there is obtained, during flight up to r spectively by ports 276 and 277 in com 25,000 eat, a gradual closure of the valve I57 as n with ham e 2 n 2 or the altitude increases, an greater closure of easing element 256 The chamber 278 as com the valve I57 whenever the w of air in the dis munication with a conduit 28 I leading om the charge line d minishes. ng iiight above discharge side of a pump 282 which, in in, has 25,000 feet the mpressor is held loaded continuits ta e c n ed y a nd i 2 3 in ously. 4o nlcation with a sump 2 The discharge co In Fig. 1 there is shown a two-stage compres wt 28! is al .connec under the control of sur, generally designated 2 ,com rising a casing Spring D d v l e 2 0 a co dllit 267 lead- 22I having chambers 222 nd 2 4 in which iming to the sum so as to p event t pressures pellers 225 and 226 are receive The impellers the Sc s h rom x in D ed ter are fixed to power shaft 228 hich is rotatably, mined Y e hamber 1 nnected b supported b bea ng 229 carried by th casing. a conduit 290 in direct communic tion with the Air is taken om an intake line 230 to the SumP- chamber 222, her it compressed b he im- Received with! e bores 2 3 a 74 is & peller 225 and then discharg d through passages VaIVe em 2 m a portion 2 slidabl 232 to the chamber 224 wh e it is compressed received Within and-separated b further by the impeller 226 d then disc arged a reduced portion 294 from an enlarged portion through conduits 233 to the b an aircra t, 295 whic engageable with the shoulder formed Opening into the discha ge de of the chambe at the j ction of the ores for controlling the 222i a assage 235 which apted to be c comm tion between thelatter Ex ending nect d u der the control of valve echanlsm longitudi ally through the valve mem r is a 231 communication witlie conduit 23s openin passage 296 opening a its left-h nd end i into the intake line 230. e valve mechanis he bore 27 which co uni'cat s through th 237 inclu s a ca ing 240 Vjng t interior re 27I wi the'conduit 252. ormed in the municating with the passa e 235, d formed in valve membe is a port 298 connecting the p ste ral th the ca h is a wal porti n 24 h e0 sage 296 in om unication with the space 300 ing a rt 242 conne ting the i terior of t e cassurrounding the reduced valve portion 294. en ing in co unication with the conduit 238. the valve member is seated, fluid delivered to the operating with the port 242 is a alve element 244 chamber 278 from th conduit 28! will pass which is connected by a stem 245 to a, pis on 246 throug he port 298 into the passage 296 and reciproeably received within a cylinder member will be ducted through the conduit 252 to the 7 attached to the valve casing. A spring 250 cylinder ember 247 for actuating the piston 246 acts between the valve casing and th piston for and mo ng the valve 244 in a closing rection g the valve ement away from the port 242 en t valve member 292 unseated, uid deng into th cylinder ember 247 beneath llvered the chamber 278 a well fluid in th the piston 246 s a conduit 252 rough which 7 cylinder ember 247 will be vented thr ugh th luid may be pplied to or ented rom the cylspace 380 surrounding the re uced valve porti n, nder inem r controlling the position of the the bore v the ports 27 th chambe 279 a alve elem nt will be appreeia ed that a supt e conduit 290 to the sump. In rder that the y or fluid e cylinder inem will result fluid pressures actin on the valve me her i a closure of the valve element all air be balanced, there is provided a bellows 'devi 13 391 connected at one end to the enlarged valve portion 295 and connected at its other end to a head member 3.03 closing the right-hand end of while there are in this application specifically described two forms which the invention may assume in practice, it will be understood that these.

the bore 214. The interior ot-thebellows de-' vice Sill is connected by ports in communication with the passage 290 so that fluid will bedelivered to its interior where it will act on the valve member. The valve member has a stem; 301 formed integral-therewith and extending i axially into a bellows device 908 which has its interior connected through the bore 214, the ports 211, the chamber 219, and the conduit 290 to the sump where the pressure is maintained equal to that at the exterior of the cabin.

In this form of the invention the flow of air through the venturi in the intake line 230 produces pressure differentials which are caused to 'act on the bellows device 259 for controlling the position of the valve member 292. As the flow of air in the intake line increases, the pressure differential also increases and tends to expand the bellows device so that the valve-member may be charge side of the chamber 222 to the conduit 238" communicating with the intake line 280. As the aircraft increases in altitude, the mass flow of air in the intake line will be reduced by reason of the reduced density, thus'causing a reduction in the pressure differential acting on the bellows device 259. Thepressures acting on opposite sides of the bellows device 308 remain balanced, however, since the pressures in the -mouth of the venturi are equal to the ambient pressures, these being the same pressures to which the interior of the bellows device 309 is subjected. This bellows device acts in this form of the invention merely as a seal between thechamber 250 and the bore 214. The reduction of the pressure differential on the bellows device 259 causes a decrease in the resistance offered by it to compression by the spring 251, and, on a predetermined reduction of the pressure difierential, the valvemember 292 will be seated to cut oil? the escape of fluid through the chamber 219 and l the conduit 290 to the sump. Fluid will then be delivered from the chamber 218 through the port 298 in the valve member, the passage 296, the

- bore 21l and the conduct 252 to the cylinder member 241 where it will act on the piston 246 and effect a. seating of the valve element 244.

The by-passing o1 fluid from the discharge side late the supply of air to the cabin of an aircraft.

It will be seen that the control means is made responsive to the mass flow-of air to or from the compressor, the mass flow varying withthe elevation of, flight and with the, speed of the compressor, and operates to vary the loading of the compressor so asto maintain the flow constant.

forms oi the same are shown for purposes of illustration, and that the invention may be modified r and embodied in various other forms without de- "parting irom its spirit or the scope of the appended claims'.

What I claim as new and desire to secure by Letters Patent is: v

' l. A compressor for delivering airto an aircraft cabin comprising, in combinatioma casing having a chamber containing'means for compressin air, an intake line for said chamber, a

discharge line through which air is discharged when a predetermined compression is reached, an

opening through which air may be discharged from said chamber before said predetermined compression is reached, valvemeans for controlling the flow of air through said opening, a flow sensitive device disposed in said discharge line, and means under the influence of said flow sensitive device and operative to control said valve means in a manner to maintain constant the flow of air in said discharge line.

2. A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having a chamber containinglrmeans for compressing air. an intake line for said chamber. a discharge line through which air is discharged when a predetermined compression is reached, an

opening through which airmay be discharged,

from said chamber before said predetermined compression is reached, valve means for controlling the flow of air through said opening, a flow sensitive device disposed in said discharge line,

-and means under the'influence of said flow sensitivedevice and tending to close said valve means as the flow of air in said discharge line decreases.

.3. Av compressor for delivering air to an aircraft cabin comprising. in combination, a casing having a chamber containing means for compressing air, an intake line for said chamber, a discharge line through which air is discharged when a predetermined compression is reached, an

opening through which air may be discharged fromsaid chamber before :said predetermined compression is reached, valve means for controlling the flow of air through said opening, a venturi connected in said discharg line, and means responsive to the flow pressure in said venturi and operative to control said valve means in a manner to maintain constant the flow of air in said discharge line. n 4. A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having achamber containing means for compressing air, an intake line for said chamber, a discharge line through which air is discharged when a predetermined compression is reached, an opening through which air may be discharged from 'said chamber before said predetermined compression is reached, valve means for controlling the flow of air through said opening, a venturi connected in said discharge line, andmeans responsive to the flow pressure in said venturi and tending to close said valve means as the flow of air through saidiventuri decreases.

5. A compressor for delivering air to an aircraftcabin comprising, in combination. a caring having a compression chamber containing means for compressing air therein, a discharge line through which air is discharged from said compression chamber to the cabin. an opening through which air may be vented from Said compression chamber, valve means for controlling the flow of air through said opening, a now sencraft cabin comprising, in combination, a casing having a compression chamber containing means for compressing air therein, a discharge line through which air is discharged from said compression chamber to the cabin, an opening through which air may be vented from said compression chamber, valve means for controlling the flow of air' through said opening, a flow sensitive device disposed in said discharge line, and

in said discharge line, and means responsive to the flow pressure insaid venturi and tending to close said valve means as the flow of air through said venturi decreases.

8. A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having a compression chamber containing means for compressing air therein, a discharge line through which air is discharged from said compression chamber to the cabin, an opening through which air may be ventedafrom said compression chamber before reaching saiddischarge line, valve means for controlling the flow oi. air

line, means including a pressure responsive device forcontrolling said valve means, said pressure responsive device having oppositely directed pressure areas, means for connecting one of said pressure areas to the flow pressure in said venturi, and means for connecting the other of said pressure areas to the pressure at the interior of the cabin.

9. A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having a compression chamber containing means for compressing air therein, a discharge line through which air is discharged from said compression chamber to the cabin, an opening through which air may be vented from said compression chamber before reaching said discharge line,- valve means for controlling the flow of air through said opening, a venturi in said discharge line, means including a pressure responsive device for controlling said valve means, said pressure responsive device having oppositely directed pressure areas, means for connecting one of said pressure areas to the flow pressure in said venturi, and means for connecting the other of said pressure areas to the pressure at the interior of the cabin, said pressure responsive device oper-'- ating on increase of the pressure difierential at its areas to effect an increased opening of said valve means.

10. A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having a compression chamber containing means 16 for compressing air therein, a discharge line through which air is discharged from said compression chamber to the cabin, an opening through which air may be vented from said compression chamber before reaching said discharge line, valve means tor controlling said opening, means including a pressure responsive device for controlling said valve means, said pressure responsive device having oppositely directed pressure areas, means for subjecting one of said areas to cabin pressure, and means for subjecting the other of said areas to the pressure surrounding said cabin.

11. A compressor for delivering air to an air-' craft cabin comprising, in combination, a casing having a compression chamber containing means for compressing air therein, a discharge line through which air is discharged from said compression chamber to the cabin, an opening through which air may be vented from said compression chamber before reaching said discharge line, valve means for controlling said opening, means including a pressure responsive device for controlling said valve means, said pressure re sponsive device havin oppositely directed pressureareas, means for subjecting one of said areas to cabin'pressure, and means for subjecting the other of said areas to the pressure surrounding said cabin, said pressure responsive device operative when the cabin pressure exceeds the surrounding, pressure by a predetermined amount to efiect a closure of said valve means.

12 A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having a compression chamber containing means for compressing air therein, a discharge line through which air is discharged from said compression chamber to the cabin, a venturi in said discharge line, an opening through which air may be vented from said compression chamber, vavle means for controlling said opening, means including pressure responsive devices for control- -through said opening, a venturi in said discharge ling saidvalve means, each of said pressure responsive devices having oppositely directed pressure areas, means for subjecting one area of each of said pressure responsive devices to cabin pressure, means for subjecting the other area of one of said pressure responsive devices to the pressures surrounding the cabin, and means for subjecting the other area of the other of said pressure responsive devices to the flow pressure in said venturi.

13. A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having a compression chamber containing means for compressing air therein, a discharge line through whichair is discharged from said compression chamber to the cabin, a venturi in said discharge line, an opening through which air may be vented irom said compression chamber, valve means for controllin said opening, means including pressure responsive devices for controlling said valve means, each oi said pressure responsive devices having oppositely directed a,444,eea '1 a 17 mined value for effectinga. closure or said valve means, and said pressure responsive device having an area subjected to the flow pressure in said venturi operative when the pressure differential between its areas decreases to a predetermined value for efiecting a closure of said valve means.

14. A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having a compression chamber containing means for compressing air therein, an intake conduit for said compressor, a discharge conduit through which air is discharged from said compression chamber to the cabin, passage means through which air may be conducted from saidcompression chamber, valve meansfor controlling said passage means, a flow sensitive device disposed in one of said conduits, and means under the infiuence of said flow sensitive device and operative to control said valve means in a manner to maintain constant the flow of air through said discharge conduit.

15. A compressor for delivering air to an aircraft cabin'com-prising, in combination, a casing having a compression chamber containing means for compressing air therein, an intake conduit for said compressor, a discharge conduit through which air is discharged from said compression chamber to the cabin, passage means through which air may be conducted from said compression chamber, valve means for controlling said passage means, a flow sensitive device disposed in said intake conduit, and means under the in-, fiuence of said flow sensitive device and operative to control said valve means in a manner to maintain'constant the flow of air through said discharge conduit.

16. A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having a compression chamber containing means for compressing air therein. an intake conduit for said compressor, a discharge conduit through which air is discharged from said compression chamber to the cabin, passage means through which air may be conducted from said compression chamber, valve means for controlling said passage means, a venturi connected in said in.- take conduit, and means including a. pressure responsive device subjected to the flow pressures in said venturi and controlling said valve means in a manner to maintain constant the flow or air through said discharge conduit.

17. A compressor for delivering air to an aircraft cabin comprising. in combination, a casing having a compression chamber containing means for compressing air therein, an intake conduit for said compressor, a discharge conduit through which air is discharged from said compression chamber to the cabin, passage means through which air may be conducted from said compression chamber, valve means for controlling said passage means, a venturi connected in said intake conduit, means including a pressure responsive device for controlling said valve means, said pressure responsive device having oppositely directed pressure areas, means for subjecting one of said pressure areas to the flow pressures in said venturi, and means for-subjecting terlor of the cabin.

18. A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having a compression chamber containing means for compressing air therein, an intake conduit for said compressor, a discharge conduit through the other of said pressure areas to the pressures at the exwhich air is discharged ,Iro m said compression chamber to the cabin, passage means through which air may be conducted from said compression chamber, valve means for controlling said passage means, a venturi connected in said intake conduit, means including a pressure responsive device for controlling said valve means, said pressure responsive device having oppositely directed pressure areas, means for subjecting one or said pressure areas to the flow pressures in said venturi, and means for subjecting the other of said pressure areas to the pressures at the exterior of the cabin, said pressure responsive device operative as the flow pressure in the venturi drops below the pressure at the exterior of the cabin to effect a gradual opening of said valve means.

19. A compressor for delivering air to an aircraft cabin comprising, in combination, a casing having compression chambers therein in which air is compressed in stages before being discharged to the cabin, means for compressing air in said chambers,.an intake conduit communicating with one of said compression chambers, a discharge conduit connecting another of said compression chambers to the cabin, passage means connecting the discharge side of one of said compression chambers to said-intake conduit, valve means for controlling said passage means, a venturi connected in said intake conduit, and means subjected to the flow pressure in said venturi and operative to control said valve means in amanner tomaintain substantially constant the flow of air in said discharge conduit.

20. A compressor comprising, in combination.

means for effecting multistage compression including elements constituting a first stage compressor and elements constituting a second stage compressor, means providing an intake for said first stage compressor, means providing a discharge for the second stage compressor, means providing a connection between said first and second stage compressors. means providing a passage connecting the discharge side oi said first stage compressor with the means providing an intake therefor, valve means controlling said passage, a flow sensitive device in said intake, and means under the influence of said flow sensitive device and operative to control said valve means in a manner to maintain constant the flow in said discharge providing means.

21. A compressor comprising a casing and rotors therein, an intake to one end of said casing, a dischargeat the other end of said casing, and passage means opening out of said casing at a point between the intake and discharge and having valve means controlling the same for variably venting pressure from said casing. and controlling means for said valve means including a venturi in said discharge and means responsive to pressure differentials in said venturi.

22. A compressor comprising a casing and rotors therein, an intake to one end of said casing, av discharge at the other end of said casing, and passage means opening out of said casing at a point between the intake and discharge and having valve means controlling the same for variably venting pressure from said casing, and controlling means for said valve means governed by the mass flow in said discharge and closing said valve progressively as mass flow tends to decrease.

23. A compressor for delivering air to an aircraft cabin comprising, in combination, a casin having a compression chamber containing means for compressing air therein, a discharge line through which air is discharged from said compression chamber to the cabin, an opening through which air may be vented from said compression chamber before reaching said discharge line, valve means for controlling the now of air through said opening, a venturi in said discharge line, means including a pressure responsive device for controlling said valve means so con nected to the latter that each moves 'with the other, said pressure responsive device having oppositely directed pressure areas, means for connecting one of said pressure areas to the flow pressure in said venturi. and means for connecting the other of said pressure areas to the pressure at the interior of the cabin.

WIN W. PAGET.

, 20 nmmcas 0mm The following references are of record in the flle of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,444,952. July '13, 1948.

WIN W. PAGET It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 12, for not withstanding read notwithstanding; column 3, line 58, for the word thereby read thereof; column 6, line 8, before latter insert the; line 41, for vavle read valve; column 8, line 8, for passageway read passage; column 9, line 51, for from read form; column 16, line 41, for vavle read valve;

and that the said Letters Patent should be vread with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 7th day of December," A. D. 1948.

THOMAS F.v MURPHY,

Assistant Commissioner of Patents. 

